Four months after a brutal assault on a U.S. diplomatic compound in Benghazi killed the ambassador to Libya and three other Americans, politicians in Washington are still railing over how diplomats were left vulnerable to attack. Yet the political furor, which now threatens to hold up President Obama’s national-security nominations, stands in stark contrast to the response in Libya itself. There, Libyans say, the investigation is nonoperational, if not effectively dead, with witnesses too fearful to talk and key police officers targeted for violent retribution. “There is no Libyan investigation. No, no, no,” says Mohamed Buisier, a political activist in Benghazi, who returned home in 2011 after decades in the U.S. “There is not even a will to investigate anything. Even for us civilians, it is very dangerous if you talk about this subject.”

The growing sense that the culprits in the Sept. 11, 2012, attack might never be caught deepened this week, when Tunisian officials released the sole suspect in custody. Citing lack of evidence, they freed Ali al-Harzi, a Tunisian citizen, though he is still restricted from traveling outside the four governorates surrounding Tunis. Al-Harzi was arrested in Turkey shortly after the Benghazi attack and deported to his home country, finally agreeing last month to a three-hour interrogation by FBI agents in Tunis, according to his lawyer Anour Ouled Ali. “He denied everything,” Ali told TIME on Thursday by phone from Tunis. “He told the FBI he was not involved at all.”

Whoever knows differently is for now not talking. And in fact, they might be dead or missing. Last week masked men surrounded the car of Benghazi’s chief of criminal investigations, Captain Abdelsalam al-Mahdawi, while he stopped at a traffic light and abducted him; he has not been seen since. His kidnapping came less than two months after Benghazi’s police chief, Faraj el-Drissi, was murdered in his Benghazi home and just weeks after armed men attempted to break into a jail in order to free the suspects in custody for el-Drissi’s murder.

Beset by criminality and awash with weapons, Benghazi is a dangerous place, and police officers like al-Mahdawi and el-Drissi had full dockets. But both men had the attack on the U.S. compound in common. “Any person who touches this file is disappearing into thin air,” says Rami el-Obeidi, a former intelligence chief for the rebels’ National Transitional Council during the 2011 revolution, who has attempted to probe the attack on his own time but has faced the frustrations of confusing and missing evidence. “Who’s leading the investigation now? No one. What’s the progress? Nothing,” he said by phone. “Anyone who has had a hand in the investigation has been killed or abducted or threatened.”

The stymied investigation seems a far cry from the assurances from Obama and Secretary of State Hillary Clinton, immediately after the attack, that the culprits would be caught. A somber Obama told White House reporters the morning after the attack, “Make no mistake, we will work with the Libyan government to bring to justice the killers who attacked our people.”

As the months have gone by, Libyans have come to doubt that will happen, believing that the attack was the work of armed militia too powerful for the weak central government in Tripoli to apprehend. In a phone interview on Wednesday, one Benghazi resident who did not want to be named told TIME that government security forces appeared to have decided not to stop the Sept. 11 attack while it was in progress. The resident said a colonel from the Ministry of Defense, a friend of his, had paid a social call to his home during the hours of the assault that night and had rebuffed pleas for help during the battle. “He began getting calls from people. One said it was war over there,” says the resident. “He said he had instructions not to interfere. Every time, he said it wasn’t serious.”

That reasoning seems unlikely to satisfy enraged Republicans in Washington, who have accused the Obama Administration of allowing fatal lapses in security for diplomats in Benghazi. On Tuesday, Senator Lindsey Graham told Fox News that the Senate should block the confirmation of John Brennan as the new CIA director “until our questions are answered” about “what transpired before, during and after the attack on our consulate.”

On the ground, however, Benghazi’s residents are slowly moving on and forgetting about the disastrous assault four months ago. The consulate building remains a burned-out ruin. And with al-Harzi out of jail in Tunisia, there is no suspect in custody for the attack. Buisier says the only thing that reminds people of the attack these days is the noise from above, apparently U.S. drones flying over eastern Libya’s main city as part of ramped-up security after the attack. Says he, “We wish they would be quieter.”